Each planet has those arrows surrounding it that mark its gravity field. If on one turn you pass through one of those arrows, the next turn's movement will be affected.
It actually can run in the command prompt! Figure out how to set your terminal window use that font, then go to game.py and find near the bottom where it says mode="pygame" and change it to say mode="terminal".
The entire game is in game.py, what the display_grid folder contains is a custom library for making command prompt UIs that I've been working on for years.
